Electronic devices, such as a portable telephone, have recently had small sizes and high performance, and accordingly had circuits which are arranged densely and which have withstand voltages decrease. This increases breakdown of the circuits caused by an electrostatic discharge pulse generated when a human body contacts terminals of the electronic devices.
In order to prevent the circuits from the breakdown caused by the electrostatic discharge pulse, a conventional laminated chip varistor disclosed in Japanese Patent Laid-Open Publication No. 08-31616 is provided between a ground and a line to which the electrostatic discharge pulse are supplied. The varistor causes the electrostatic discharge pulse to bypass the circuits to reduce a voltage applied to the circuits.
Electronic devices have small sizes and high performance and accordingly, the number of components to address the electrostatic discharge pulse. Particularly for varistors, not only a single varistor but also a varistor array including plural varistors are demanded. Such varistors are demanded to be thin to provide small and thin electronic devices.
Zinc-oxide based material, which the conventional laminated chip varistor disclosed in Japanese Patent Laid-Open Publication No. 08-31616 employs, has a small strength to bending. The conventional varistor necessarily has a certain thickness to provide a predetermined strength, thus hardly having a small thickness. For example, a commercially-available laminated chip varistor having a length of about 1.6 mm and a width of 0.8 mm needs to have a thickness larger than 0.8 mm. If having a thickness smaller than this, the laminated chip varistor needs to have a smaller size, thus hardly providing a thin and large varistor. Accordingly, it is difficult to provide a varistor array including a large number of varistors.